JEB desktop wallpaper calendar 2016

Journal of Experimental Biology partnership with Dryad

Anatomically diverse butterfly scales all produce structural colours by coherent scattering
Richard O. Prum, Tim Quinn, Rodolfo H. Torres
  1. Fig. 1.

    Photographs of the butterfly species examined. Uraniidae: (A) Urania fulgens; Papilionidae: (B) Papilio ulysses, (C) Papilio zalmoxis, (D) Parides sesostris, (E) Troides brookiana, (F) Troides urvillianus, (G) Troides priamus priamus (phenotypically similar to the green T. p. hecuba examined); Lycaenidae: (H) Celastrina ladon, (I) Callophrys dumetorum, (J) Mitoura gryneus and (K) Parrhasius m-album (very similar and closely related to the P. moctezuma examined); Nymphalidae: (L) Morpho aega. Photos are of upper wing surfaces, except for Callophrys dumetorum (I) and Mitoura gryneus (J), which are underwing surfaces. Not to scale. Specimens courtesy of the Yale Peabody Museum of Natural History Department of Entomology.

  2. Fig. 2.

    Light microscope photographs of the structurally coloured scales of a sample of the Lepidoptera examined. (A) Urania fulgens blue, (B) Urania fulgens green, (C) Urania fulgens showing the transition between blue and green patches, (D,E) Papilio ulysses, (F) Papilio zalmoxis, (G) Parides sesostris, (H) Troides urvillianus, (I) Troides priamus. All images at 63×, except C (20×) and D (40×). Classification of species examined is given in Table 1.

  3. Fig. 3.

    Light microscope photographs of the structurally coloured scales of a sample of the Lepidoptera examined. (A) Celastrina ladon, (B) Callophrys dumetorum, (C) Mitoura gryneus, (D) Parrhasius moctezuma and (E,F) Morpho aega. All images at 63×, except D (70×) and E (7.5×). Classification of species examined is given in Table 1.

  4. Fig. 4

    Transmission electron micrographs (TEMs) of sections of the structurally coloured scales of a sample of the lepidopteran species examined. (A,B) Urania fulgens blue, (C) Urania fulgens green, (D,E) Papilio ulysses, (F,G) Papilio zalmoxis, (H-J) Parides sesostris, (K,L) Troides brookiana. Scale bars, 500 nm (A,D, F,G), 200 nm (B,C,E,J,L), 2 μm (H), and 1 μm (K).

  5. Fig. 5.

    Transmission electron micrographs (TEMs) of the structurally coloured scales of a sample of the Lepidoptera examined. (A-B) Troides urvillianus, (C) Troides priamus, (D) Celastrina ladon, (E,F) Callophrys dumetorum, (G) Mitoura gryneus, (H) Parrhasius moctezuma, (I) Morpho aega. Scale bars, 500 nm (A,D,E,H), 200 nm (B,C,F,G), and 2 μm (L).

  6. Fig. 6.

    Two-dimensional Fourier power spectra of transmission electron micrographs of structural colour producing butterfly scale nanostructures (Figs 4, 5). (A) Urania fulgens blue (Fig. 4B), (B) Papilio ulysses (Fig. 4E), (C) Papilio zalmoxis (Fig. 4G), (D) Parides sesostris (Fig. 4J), (E) Troides brookiana (Fig. 4L), (F) Troides urvillianus, (G) Callophrys dumetorum (Fig. 5F), (H) Parrhasius moctezuma (Fig. 5H) and (I) Morpho aega (not illustrated). Colour scale (from blue to red) indicates the relative magnitude of the squared Fourier components, which are dimensionless quantities. Direction from the origin indicates the direction of the 2D component waves in the image, and the distance from the origin indicates the spatial frequency (cycles/nm) of each Fourier component. The Fourier power peaks (red pixels) demonstrate predominant periodicities at intermediate spatial frequencies. The distance from the origin is inversely proportional to the wavelength of the coherently scattered colour.

  7. Fig. 7.

    Radial averages of two-dimensional Fourier power spectra from TEM micrographs of structural colour producing butterfly scale nanostructures (Fig. 6). (A) Urania fulgens blue, (B) Parides sesostris, (C) Troides brookiana, (D) Troides urvillianus, (E) Mitoura gryneus. The shaded zone shows the range of spatial frequencies that are likely to produce coherent scattering of visible light wavelengths.

  8. Fig. 8.

    Measured reflectance spectra (blue) and Fourier predicted reflectance spectra (orange) for the structurally coloured butterfly nanostructures illustrated in Fig. 4. (A) Urania fulgens blue, (B) Urania fulgens green, (C) Papilio ulysses, (D) Papilio zalmoxis, (E) Parides sesostris, (F) Troides brookiana.

  9. Fig. 9.

    Measured reflectance spectra (blue) and Fourier predicted reflectance spectra (orange) for the structurally coloured butterfly nanostructures illustrated in Fig. 5. (A) Troides urvillianus, (B) Troides priamus, (C) Celastrina ladon, (D) Callophrys dumetorum, (E) Mitoura gryneus, (F) Parrhasius moctezuma and (G) Morpho aega.

  10. Fig. 10.

    Fourier analysis of a concavity from a structurally coloured scale of Papilio ulysses. (A) Transmission electron micrograph of a single scale surface concavity from Papilio ulysses. (B) 2D Fourier power spectrum of A showing an arc-shaped distribution of Fourier power peaks (red pixels) above and below the origin that is created by the concave distortion of the fundamentally laminar array of air bubbles in the scale. The result is a broadening of the range angles over which the light back-scattered to the observer will maintain the same peak hue.